: X-ray diffraction data to evaluate the welding residual stresses variation in welded joints under cyclic loads

This article presents the results for the measurement of the residual stresses by means of X-ray diffraction in butt-welded specimens subjected by cyclic loads. To do it a procedure was proposed and a study case was developed. The material studied was AISI 1018 steel. The process used to join the plates was semiautomatic welding. Residual stresses were measured at zero, 2 500, 5 000, 7 500 and 10 000 load cycles respectively. For this a diffractometer XRD; PANalytical Empyrean model was utilized to obtain a residual stresses and a MTS810 servohydraulic testing machine to mechanical test. The mechanical characterization of the joint was performed to determine the parameters of the fatigue load cycle. The residual stresses were measured before starting to apply the cyclic loads and subsequently they were measured again every 2 500 load cycles. As the main result of the application of this procedure to the joint studied, it was obtained that in the analyzed position, the residual stresses were compression and increased in absolute value with the action of the cyclic loads. For each diffractometric are showed a data of the position and the light intensity. Also are showed the incidence angle and the distance between adjacent lattice planes.

本文报道了采用X射线衍射法对承受循环载荷的对接焊接试样开展残余应力测试的研究结果。为此，本文提出了一套测试流程并完成了实例研究，测试材料为AISI 1018钢。试样板材采用半自动焊接工艺进行连接。测试分别在0、2500、5000、7500及10000次载荷循环节点进行残余应力测量。本次测试采用X射线衍射（XRD）仪（PANalytical Empyrean型号）采集残余应力数据，并使用MTS810伺服液压试验机开展力学试验。为确定疲劳载荷循环的相关参数，研究人员对焊接接头进行了力学性能表征。残余应力测试首先在循环载荷加载前完成，之后每完成2500次载荷循环即进行一次复测。针对所研究接头应用该测试流程的主要结果表明：在被测位置处，残余应力为压应力，且其绝对值随循环载荷的作用持续增大。每份衍射测试数据均包含测试位置与光强信息，同时还给出了入射角与相邻晶面间距。